{keyword}') Union All Select Null,null,null,null,null-- Dyyf 〈2025〉

: This is the SQL comment syntax. It tells the database to ignore everything that follows it, which prevents the remaining "real" code from causing a syntax error.

: This is likely a "fingerprint" or a random string used by automated security scanners (like Burp Suite or SQLmap) to identify which specific payload successfully triggered a response. Why you are seeing this {KEYWORD}') UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- DyYf

: This part attempts to "break out" of a predefined search query. The ') is used to close a string literal and a parenthesis in the backend code, allowing the attacker to append their own commands. : This is the SQL comment syntax